Add trybuild tests for axum-debug (#501)

The things are also covered by the doc tests but this also gives us
assertions on the errors produced, which is the whole point of this
crate :)

axum-debug/tests/fail/argument_not_extractor.rs

@@ -0,0 +1,6 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+async fn handler(foo: bool) {}
+
+fn main() {}

axum-debug/tests/fail/argument_not_extractor.stderr

@@ -0,0 +1,11 @@
+error[E0277]: the trait bound `bool: FromRequest` is not satisfied
+ --> tests/fail/argument_not_extractor.rs:4:23
+  |
+4 | async fn handler(foo: bool) {}
+  |                       ^^^^ the trait `FromRequest` is not implemented for `bool`
+  |
+note: required by a bound in `handler::{closure#0}::debug_handler`
+ --> tests/fail/argument_not_extractor.rs:4:23
+  |
+4 | async fn handler(foo: bool) {}
+  |                       ^^^^ required by this bound in `handler::{closure#0}::debug_handler`

axum-debug/tests/fail/not_a_function.rs

@@ -0,0 +1,6 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+struct A;
+
+fn main() {}

axum-debug/tests/fail/not_a_function.stderr

@@ -0,0 +1,5 @@
+error: expected `fn`
+ --> tests/fail/not_a_function.rs:4:1
+  |
+4 | struct A;
+  | ^^^^^^

axum-debug/tests/fail/not_async.rs

@@ -0,0 +1,6 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+fn handler() {}
+
+fn main() {}

axum-debug/tests/fail/not_async.stderr

@@ -0,0 +1,5 @@
+error: handlers must be async functions
+ --> tests/fail/not_async.rs:4:1
+  |
+4 | fn handler() {}
+  | ^^

axum-debug/tests/fail/not_send.rs

@@ -0,0 +1,9 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+async fn handler() {
+    let rc = std::rc::Rc::new(());
+    async {}.await;
+}
+
+fn main() {}

axum-debug/tests/fail/not_send.stderr

@@ -0,0 +1,21 @@
+error: future cannot be sent between threads safely
+ --> tests/fail/not_send.rs:4:10
+  |
+4 | async fn handler() {
+  |          ^^^^^^^ future returned by `handler` is not `Send`
+  |
+  = help: within `impl Future`, the trait `Send` is not implemented for `Rc<()>`
+note: future is not `Send` as this value is used across an await
+ --> tests/fail/not_send.rs:6:5
+  |
+5 |     let rc = std::rc::Rc::new(());
+  |         -- has type `Rc<()>` which is not `Send`
+6 |     async {}.await;
+  |     ^^^^^^^^^^^^^^ await occurs here, with `rc` maybe used later
+7 | }
+  | - `rc` is later dropped here
+note: required by a bound in `handler::{closure#0}::debug_handler`
+ --> tests/fail/not_send.rs:4:10
+  |
+4 | async fn handler() {
+  |          ^^^^^^^ required by this bound in `handler::{closure#0}::debug_handler`

axum-debug/tests/fail/self_receiver.rs

@@ -0,0 +1,20 @@
+use axum_debug::debug_handler;
+use axum::{async_trait, extract::{FromRequest, RequestParts}};
+
+struct A;
+
+#[async_trait]
+impl FromRequest for A {
+    type Rejection = ();
+
+    async fn from_request(_req: &mut RequestParts) -> Result<Self, Self::Rejection> {
+        unimplemented!()
+    }
+}
+
+impl A {
+    #[debug_handler]
+    async fn handler(self) {}
+}
+
+fn main() {}

axum-debug/tests/fail/self_receiver.stderr

@@ -0,0 +1,5 @@
+error: `#[debug_handler]` is not supported on methods
+  --> tests/fail/self_receiver.rs:17:22
+   |
+17 |     async fn handler(self) {}
+   |                      ^^^^

axum-debug/tests/fail/too_many_extractors.rs

@@ -0,0 +1,24 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+async fn handler(
+    e1: String,
+    e2: String,
+    e3: String,
+    e4: String,
+    e5: String,
+    e6: String,
+    e7: String,
+    e8: String,
+    e9: String,
+    e10: String,
+    e11: String,
+    e12: String,
+    e13: String,
+    e14: String,
+    e15: String,
+    e16: String,
+    e17: String,
+) {}
+
+fn main() {}

axum-debug/tests/fail/too_many_extractors.stderr

@@ -0,0 +1,12 @@
+error: too many extractors. 16 extractors are allowed
+note: you can nest extractors like "a: (Extractor, Extractor), b: (Extractor, Extractor)"
+  --> tests/fail/too_many_extractors.rs:5:5
+   |
+5  | /     e1: String,
+6  | |     e2: String,
+7  | |     e3: String,
+8  | |     e4: String,
+...  |
+20 | |     e16: String,
+21 | |     e17: String,
+   | |________________^

axum-debug/tests/fail/wrong_return_type.rs

@@ -0,0 +1,8 @@
+use axum_debug::debug_handler;
+
+#[debug_handler]
+async fn handler() -> bool {
+    false
+}
+
+fn main() {}

axum-debug/tests/fail/wrong_return_type.stderr

@@ -0,0 +1,11 @@
+error[E0277]: the trait bound `bool: IntoResponse` is not satisfied
+ --> tests/fail/wrong_return_type.rs:4:23
+  |
+4 | async fn handler() -> bool {
+  |                       ^^^^ the trait `IntoResponse` is not implemented for `bool`
+  |
+note: required by a bound in `handler::{closure#0}::debug_handler`
+ --> tests/fail/wrong_return_type.rs:4:23
+  |
+4 | async fn handler() -> bool {
+  |                       ^^^^ required by this bound in `handler::{closure#0}::debug_handler`